News/Notices

Feb. 17, 11:45, Wei Ji Ma. Optimality and Probabilistic Computation in Visual Categorization

Rob McPeek

SUNY Optometry

Target selection for visually-guided action

Most real-world visual scenes are crowded with many different competing objects. In order to interact effectively with the world, we must select a single object, from the multitude of possibilities, as the target for visually-guided action. Thus, target selection is a fundamental process required for visually-guided behavior. We have studied target selection for saccadic eye movements in the superior colliculus (SC), a midbrain structure involved in the execution of saccades. We found that SC activity is not just related to saccade execution; it is also correlated with the antecedent process of target selection. To determine whether the SC plays a causal role in saccade target selection, we temporarily inactivated a portion of the SC and tested in a target selection task. We found that focal SC inactivation leads to systematic changes in the choice of saccade targets, establishing that the SC does play a causal role in saccade target selection.  
Is the SC's role in target selection limited to eye movements? To pursue this question, we are now investigating target selection for visually-guided reaching movements. We find that SC activity is correlated with reach target selection even when fixation is maintained. Even more surprisingly, we have discovered that temporary SC inactivation disrupts the selection of visual targets for reaching movements. These results suggest that the SC is part of a general-purpose target-selection system which is used to guide a variety of visually-guided actions. 
 
 
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